Male reproductive Flashcards
define epididymis
- connects the rete testis to the vas deferens
- function = storage, maturation and transport of sperm
define vas deferens
- sperm transport and storage tube between epididymis and the seminal vesicles
describe seminal vesicle
- produces about 60% of fluid portion of ejaculate (semen)
- seminal fluid consists of:
- -> fructose for energy
- -> prostaglandins to make cervical enviornment more favorable for sperm
- -> fibrinogen causes semen to coagulate following ejaculation
- -> seminogelin attaches to sperm and serves to suppress motility of sperm in coagulated semen
describe prostate
- secretes milky fluid that contains:
- -> profibrinolysin which dissolves the coagulated semen, thus freeing sperm
- -> HCO3 neutralizes the acidic environment of their cervix allowing sperm to become more active
- -> PSA (prostate specific antigen) hydrolyzes seminogelin, which increases sperm motility
define bulbourethral gland
- secretes mucus into the urethra upon arousal
- -> thought to clean the lumen of urethra and act as a lubricant
define GnRH
- synthesized and released by hypothalamus
- causes the release of LH and FSH
define LH
- LH binds to receptors on Leydig cells and stimualtes testosterone production and secretion
- Testosterone diffuses to Sertoli cells to facilitate spermatogenesis
Define FSH
- GnRh causes the release of FSH
- FSH stimulates Sertoli cells to produce ABP (which concentrates testosterone at site of spermatogenesis)
- FSH controls sertoli cell proliferation and seminiferous tubule growth
- Stimualtes Sertoli cells to produce INHIBIN (inhibits FSH production)
Define androgen binding protein (ABP)
- facilitates spermatogenesis by concentration testosterone at site of spermatogenesis
How is the HPG-axis regulated
- Testosterone inhibits the release of both LH and FSH along with the release of GnRH by the hypothalamus
- Testosterone can also be converted to DHT and estradiol (both which exert negative feedback
- FSH stimulates production of INHIBIN in the sertoli cells
- -> inhibin selectively inhibits FSH production by anterior pituitary
describe function of sertoli cells
- FSH controls sertoli cell
- sertoli cells produce inhibin which inhibits pituitary gonadroptropes (LH and FSH)
- sertoli cells produce ABP which concentrates testosterone at site of spermatogenesis
function of Leydig cells
- stimualtes testosterone production and secretion
what are the effects of testosterone
- Internal genitalia = wolffian development during gestation
- skeletal muscle = increase mass and strength during puberty
- increased erythropoiesis (more RBC)
- bone
what are the effects of Dihydrotestosterone
- External genitalia = differentiation during gestation, maturation during puberty, adulthood prostatic disease
- increases growth of hair follicles during puberty
What are the effects of Estradiol
- epiphyseal closure and increased bone density
- libido
define spermiogenesis
- process in which spermatids differentiate into sperm by becoming elongated and developing acrosomal cap and flagellum
define spermiation
- process of sperm being released into the lumen of the seminiferous tubule
describe spermatogenesis
1) primordial germ cells migrate to testes and line the seminiferous tubules (called spermatogonia)
2) at time of puberty, GnRH secretion increases leading to increase in testosterone synthesis by testes
3) initiates spermatogonia to begin to proliferate
4) cells corss the tigh junctions between sertoli cells and enter adluminal compartment
5) continue to migrate towards lumen and start differentiating into spermatids (haploid cells
describe primary hypogonadism
- testicular dysfunction leads to decrease in testoserone production but increased LH and FSH levels
- result from cryptorchidism or klinefelter syndrome
describe secondary hypogonadism
- decrease in circulating gonadotrophins
- low testosterone in the setting of normal to low LH and FSH
- Kallmann syndrome
list the stages of male sexual act
1) erection
2) lubrication
3) emission
4) ejacualtion
define lubrication
parasympathetic impulses cause the bulbourethral gland to secret mucus to aid in lubrication
define emission
- sympathetic impulses induce movement of spermatozoa into proximal part of the urethra
define ejaculation
- reflex reaction triggered by entry of semen into proximal urethra
- singals from somatic motor efferents travel through pudendal nerve and cause rhythemic contractions of muscles at base of penis to push the semen out
describe initiation of erection
- active parasympathetic induces dialtion of penile arteries and smooth muscle cells of the corpus cavernosum and corpus spongiosum
- nerve terminals release Ach, NO and vasoactive intestinal peptide (VIP)
- -> NO diffuses into vascular smooth muscles causing the activation of gunylyl cyclanse and the consequent production of cGMP
- -> cGMP causes relaxation of these smooth muscles cells causing blood to fill the sinuses
